1. Field of the Invention
The present invention pertains to a button of a switch assembly, where the switch assembly is of the rocking or pivoting type of switch assembly. The invention more particularly concerns the retention of the button in the switch assembly during application of external forces or impact loading to the switch assembly.
2. Discussion of the Background
Switch assemblies are well known in the art where a button pivotally mounts to a housing. Automotive manufacturers are increasingly integrating many functions, such as switches, on the steering column, on stalks projecting outward from the steering column, and on the steering wheel. Such placement of switch assemblies is ergonomically desirable.
Automotive component manufacturers are under pressure from the leaders of the automotive industry to provide components which are considered to be safe during a crash of an automobile. Safe-type components are typically covered with a soft, foam-like material. Another solution is to prevent components from becoming dislodged and flying about the cabin area of the automobile. Flying components can cause serious injuries to the occupants of the cabin area. During a crash or collision, the components are subject to large de-acceleration levels. Also, during deployment of an airbag, components mounted on the steering wheel are subject to large acceleration levels. Currently, automobile manufacturers are investigating the possibility of reducing the magnitude of the force used to deploy airbags, since the deployment force is so large and is capable of causing injury to the occupants of the cabin. Such examples clearly illustrate the potential for injury to occupants when components become dislodged. Thus, there is great demand for components which do not become dislodged when subject to the acceleration levels experienced during deployment of an airbag or during a crash.
Furthermore, the automobile manufacturers require that the solution to such a problem be inexpensive and easy to install. To-date, no prior art solution exists that is economical to manufacture and easy to install, while being resistant to large levels of acceleration. Most switch assemblies employ trunions that engage with pivot holes. Where either the pivot hole or the trunion can be located on the button and the other of the two features is located on the housing. Typically, the trunion feature displaces the rib containing the pivot hole feature. Then the trunion snaps into place with the pivot hole feature. High impact forces can dislodge the button from the housing, since the rib having the pivot hole can deflect and become dismounted from the trunion. Attempts have been made to ensure the retention of the button by increasing the stiffness of the parts so that when they snap together they do so with greater force. However, increasing the stiffness of the parts has led to the overstressing of the parts during assembly thus leading to failure of the parts. An inexpensive switch is one that can elastically snap together, however, the fact that the parts must flex enough during assembly, limits the rigidity of the elastic members. Such requirements adversely effect the retaining abilities of the switch assembly.
Thus, there is a need for an inexpensive, reliable, button of a switch assembly that can be easily mounted on a steering wheel of an automobile and where the button will not become dislodge during deployment of an airbag located in the steering wheel.